Frame formats and timing parameters in sub-1 ghz networks

ABSTRACT

A method includes selecting a frame format for use in transmission of a packet via a wireless network. The transmission is associated with a particular bandwidth. The selected frame format is a first frame format if the particular bandwidth is equal to a threshold bandwidth. The selected frame format is the first frame format or a second frame format if the particular bandwidth is greater than the threshold bandwidth. The second frame format includes a first portion and a second portion. The first portion includes a short training field (STF), a long training field, and a signal A field, and the second portion includes a data portion including a second STF, one or more signal B fields, and a data field. The method further includes generating the packet in accordance with the selected frame format and one or more timing parameters and sending the packet.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority from commonly owned U.S.Provisional Patent Application No. 61/619,338 filed Apr. 2, 2012, andU.S. Non-Provisional patent application Ser. No. 13/782,451 filed Mar.1, 2013, the contents of which are expressly incorporated herein byreference in their entirety.

BACKGROUND

1. Field

The present disclosure relates to wireless data communications.

2. Background

Advances in technology have resulted in smaller and more powerfulcomputing devices. For example, there currently exist a variety ofportable personal computing devices, including wireless computingdevices, such as portable wireless telephones, personal digitalassistants (PDAs), and paging devices that are small, lightweight, andeasily carried by users. More specifically, portable wirelesstelephones, such as cellular telephones and Internet Protocol (IP)telephones, can communicate voice and data packets over wirelessnetworks. Many such wireless telephones incorporate additional devicesto provide enhanced functionality for end users. For example, a wirelesstelephone can also include a digital still camera, a digital videocamera, a digital recorder, and an audio file player. Also, suchwireless telephones can execute software applications, such as a webbrowser application that can be used to access the Internet. As such,these wireless telephones can include significant computingcapabilities.

In some communication systems, networks may be used to exchange messagesamong several interacting spatially-separated devices. Networks may beclassified according to geographic scope, which could be, for example, ametropolitan area, a local area, or a personal area. Such networks maybe designated respectively as a wide area network (WAN), a metropolitanarea network (MAN), a local area network (LAN), a wireless local areanetwork (WLAN), or a personal area network (PAN). Networks may alsodiffer according to the switching/routing techniques used tointerconnect the various network nodes and devices (e.g., circuitswitching vs. packet switching), the type of physical media employed fortransmission (e.g., wired vs. wireless), and the set of communicationprotocols used (e.g., Internet protocol suite, SONET (SynchronousOptical Networking), Ethernet, etc.).

Wireless networks may be preferred when network elements are mobile andhave dynamic connectivity needs or if the network architecture is formedin an ad hoc, rather than fixed, topology. Wireless networks may employintangible physical media in an unguided propagation mode usingelectromagnetic waves in the radio, microwave, infra-red, optical, orother frequency bands. Wireless networks may advantageously facilitateuser mobility and rapid field deployment when compared to fixed wirednetworks.

Devices in a wireless network may transmit/receive information withother devices/systems. The information may include packets. The packetsmay include overhead information (e.g., header information, packetproperties, etc. related to routing the packets through the network) aswell as data (e.g., user data, multimedia content, etc. in a payload ofthe packet).

SUMMARY

Wireless networking systems can operate at various frequency ranges andat various bandwidths. Institute of Electrical and Electronics Engineers(IEEE) 802.11 is a set of industry standards, protocols, and groupsassociated with wireless networking. For example, IEEE 802.11a, 802.11b,802.11g, and 802.11n are wireless networking standards that may be usedin customer premise wireless networking, such as in a home or officeenvironment. “In progress” IEEE 802.11 standards include 802.11ac(entitled “Very High Throughput in <6 GHz”), 802.11ad (entitled “VeryHigh Throughput in 60 GHz”), 802.11af (entitled “Wireless Local AreaNetwork (LAN) in Television White Space”), and 802.11ah (entitled “Sub-1GHz”).

In particular, IEEE 802.11ah is associated with wireless communicationat frequencies less than one gigahertz. Such communication may be usefulfor devices having low duty cycles, such as sensors. To illustrate, awireless sensor that communicates over an IEEE 802.11ah network may wakeup for a few seconds to perform a few measurements, communicate resultsof the measurements to a destination, and then sleep for a few minutes.An IEEE 802.11ah wireless network may support communication using 1, 2,3, or 4 spatial streams at 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHzbandwidths.

Systems and methods of controlling characteristics of messages in sub-1GHz networks (e.g., IEEE 802.11ah networks) are disclosed. For example,prior to sending a message (e.g., a packet) from a transmitter to areceiver, the transmitter may choose a modulation and coding scheme(MCS) to apply to the message. More than one MCS may be available foreach bandwidth/spatial stream combination. An index value correspondingto the chosen MCS may be included in the message. For example, an MCSindex may be included in a signal (SIG) field of a physical layer (PHY)preamble of the message. When the message is received, the receiver mayuse the MCS index to determine various message characteristics that maybe useful in decoding the message. In one implementation, thetransmitter and the receiver may each store or otherwise have access todata structures (e.g., tables) that can be searched by MCS index.

Packets communicated via a sub-1 GHz wireless network may comply withone of multiple frame formats (e.g., a single user (SU) or “short”format and a multi user (MU) or “long” format) and may comply withvarious timing parameters. The frame format may identify what fields areincluded in the packet and the order of the fields in the packet. Thetiming parameters may indicate quantities and field durations associatedwith the packet. The frame format and/or timing parameters may be usedin encoding and/or decoding of the packet. A data structure (e.g.,table) indicating timing parameters for different frame formats may bestored at or otherwise accessible to transmitters and receivers.

Packets communicated via a sub-1 GHz wireless network may also besubjected to tone scaling. For example, different fields of a packet maybe tone scaled by a different amount. Tone scaling parameters may beused in encoding and/or decoding of the packet. A data structure (e.g.,table) indicating tone scaling parameters for different fields may bestored at or otherwise accessible to transmitters and receivers.

In a particular embodiment, a method includes selecting, at atransmitter, a frame format for use in communicating a packet via asub-one gigahertz wireless network operating at a particular bandwidth,where the frame format is selected based at least in part on theparticular bandwidth. The method also includes determining one or moretiming parameters based on the selected frame format and the particularbandwidth. The method further includes generating the packet inaccordance with the selected frame format and the one or more timingparameters. The method includes sending the packet from the transmitterto a receiver. The selected frame format is a short frame format whenthe particular bandwidth is one megahertz, and the selected frame formatis the short frame format or a long frame format when the particularbandwidth is greater than one megahertz.

In another particular embodiment, a non-transitory processor-readablemedium stores one or more data structures. The one or more datastructures indicate timing parameters for a short frame format and along frame format of a sub-one gigahertz wireless network for each of aplurality of operating bandwidths of the sub-one gigahertz wirelessnetwork. The timing parameters include a number of complex datasubcarriers, a number of pilot subcarriers, a number of totalsubcarriers excluding guards, a highest data subcarrier index, asubcarrier frequency spacing, an inverse discrete Fourier transformperiod, a discrete Fourier transform period, a guard interval duration,a double guard interval duration, a short guard interval duration, orany combination thereof. Alternately, or in addition, the timingparameters include an orthogonal frequency-division multiplexing (OFDM)symbol duration with long guard intervals, an OFDM symbol duration withshort guard intervals, an OFDM symbol duration, a number of bits in aSERVICE field, a number of tail bits per binary convolution codeencoder, a short training field (STF) duration, a long training field(LTF) duration, a signal field (SIG) duration, a signal A field (SIG-A)duration, a multiple-input multiple-output LTF (MIMO-LTF) duration, along format STF duration, a signal B field (SIG-B) duration, or anycombination thereof.

In another particular embodiment, an apparatus includes a memory storingone or more data structures. The one or more data structures indicatetiming parameters for each of a plurality of frame formats of a sub-onegigahertz wireless network and a plurality of bandwidths of a sub-onegigahertz wireless network. The apparatus also includes a processorcoupled to the memory and configured to select a frame format for use incommunicating a packet via the sub-one gigahertz wireless networkoperating at a particular bandwidth, where the frame format is selectedbased at least in part on the particular bandwidth. The processor isalso configured to determine one or more timing parameters based on theselected frame format and the particular bandwidth. The processor isfurther configured to generate the packet in accordance with theselected frame format and the one or more timing parameters. Theselected frame format is a short frame format when the particularbandwidth is one megahertz, and the selected frame format is the shortframe format or a long frame format when the particular bandwidth isgreater than one megahertz.

In another particular embodiment, an apparatus includes means forstoring one or more data structures. The one or more data structuresindicate timing parameters for a plurality of frame formats and aplurality of bandwidths of a sub-one gigahertz wireless network. Theapparatus also includes means for selecting a frame format for use incommunicating a packet via the sub-one gigahertz wireless networkoperating at a particular bandwidth, where the frame format is selectedbased at least in part on the particular bandwidth. The apparatusfurther includes means for determining the one or more timing parametersbased on the selected frame format and the particular bandwidth. Theapparatus includes means for generating the packet in accordance withthe selected frame format and the one or more timing parameters.

One particular advantage provided by at least one of the disclosedembodiments is an ability to control various characteristics of messages(e.g., packets) communicated via a sub-1 GHz wireless network. Forexample, such characteristics may include MCS, frame format, timingparameters, tone scaling parameters, and/or other characteristicsdescribed herein.

Other aspects, advantages, and features of the present disclosure willbecome apparent after review of the entire application, including thefollowing sections: Brief Description of the Drawings, DetailedDescription, and the Claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of a particular embodiment of a system operable tocontrol message characteristics in a sub-1 GHz wireless network;

FIGS. 2A, 2B, and 2C illustrate particular examples of the MCS tables ofFIG. 1;

FIGS. 3A, 3B, and 3C illustrate additional particular examples of theMCS tables of FIG. 1;

FIGS. 4A, 4B, 4C, and 4D illustrate additional particular examples ofthe MCS tables of FIG. 1;

FIGS. 5A, 5B, 5C, and 5D illustrate additional particular examples ofthe MCS tables of FIG. 1;

FIGS. 6A, 6B, 6C, and 6D illustrate additional particular examples ofthe MCS tables of FIG. 1;

FIGS. 7A, 7B, 7C, and 7D illustrate additional particular examples ofthe MCS tables of FIG. 1;

FIGS. 8A and 8B illustrate additional particular examples of the MCStables of FIG. 1;

FIGS. 9A, 9B, 9C and 9D illustrate particular examples of the MCS tablesof

FIG. 1 when a single encoder is used for all possible bandwidths andnumbers of spatial streams;

FIGS. 10A, 10B, 10C and 10D illustrate additional particular examples ofthe MCS tables of FIG. 1 when a single encoder is used for all possiblebandwidths and numbers of spatial streams;

FIG. 11 is a flowchart of a particular embodiment of a method ofdetermining message characteristics in a sub-1 GHz wireless networkbased on an MCS index;

FIG. 12 is a flowchart of a particular embodiment of a method ofcontrolling message characteristics in a sub-1 GHz wireless networkbased on an MCS index;

FIG. 13 is a diagram to illustrate particular embodiments of frameformats that may be used to with respect to the packet of FIG. 1;

FIG. 14 illustrates particular examples of the timing parameters of FIG.1;

FIG. 15 is a flowchart of a particular embodiment of a method ofcontrolling a frame format and timing parameters in a sub-1 GHz wirelessnetwork;

FIG. 16 illustrates particular examples of the tone scaling parametersof FIG. 1;

FIG. 17 is a flowchart of a particular embodiment of a method ofcontrolling tone scaling parameters in a sub-1 GHz wireless network; and

FIG. 18 is a block diagram of a mobile communication device includingcomponents that are operable to control characteristics of messages in asub-1 GHz wireless network.

DETAILED DESCRIPTION

FIG. 1 is a diagram of a particular embodiment of a system 100 operableto control message characteristics in a sub-1 GHz wireless network 140.In a particular embodiment, the sub-1 GHz wireless network 140 operatesin accordance with an IEEE 802.11ah protocol. The wireless network 140may support multiple bandwidths and one or more spatial streams. Forexample, the wireless network 140 may support 1 MHz, 2 MHz, 4 MHz, 8MHz, and 16 MHz bandwidths and the use of 1, 2, 3, or 4 spatial streams.

The system 100 includes a transmitter 110 and a receiver 120. It shouldbe noted that although a single transmitter and receiver are shown inFIG. 1, alternate embodiments may include more than one transmitter andor receiver. The transmitter 110 and the receiver 120 may communicatevia packets, such as an illustrative packet 130. It should be noted thatalthough a dedicated transmitter 110 and a dedicated receiver 120 areshown in FIG. 1, some devices (e.g., transceivers or mobilecommunication devices that include a transceiver) may be capable of bothpacket transmission as well as packet reception. Thus, the wirelessnetwork 140 supports two-way communication.

The transmitter 110 may store or otherwise have access to MCS tables111, timing parameters 112, and tone scaling parameters 113. Thetransmitter 110 may include a packet creator/encoder 114 that isconfigured to create and encode packets, such as the packet 130. Thecreator/encoder 114 may set one or more characteristics of the packet130 during the creation and encoding process.

For example, the creator/encoder 114 may select a particular modulationand coding scheme (MCS) of the packet 130 from a plurality of availableMCSs. Which MCSs are available may depend on the bandwidth and thenumber of spatial streams in use at the wireless network 140. In aparticular embodiment, devices connected to the wireless network 140 maybe notified of the bandwidth and number of spatial streams by an accesspoint associated with the wireless network (e.g., via a beacon, proberesponse, or other control message). Devices may also determine networkcharacteristics, such as bandwidth and number of spatial streams, byexamining messages communicated via the wireless network 140. Whichparticular MCS is selected may be based on factors such as channelconditions, distance, and desired data rate. The transmitter 110 maystore or otherwise have access to one or more MCS tables 111 thatidentify the available MCSs for each combination of bandwidth and numberof spatial streams. The creator/encoder 114 may insert an index of theselected MCS into the packet 130. In a particular embodiment, the MCSindex may be included in a signal (SIG) field of a physical layer (PHY)preamble of the packet 130. The MCS index may indicate a modulationscheme and a coding rate of the packet 130 and may also indicate or beuseable to derive additional encoding characteristics of the packet 130,such as a number of bits per subcarrier symbol, a number of datasymbols, a number of pilot symbols, a number of coded bits perorthogonal frequency-division multiplexing (OFDM) symbol, a number ofdata bits per (OFDM) symbol, a number of encoders used to encode thepacket 130, data rate(s), and/or a guard interval. Particular examplesof MCS tables are described with reference to FIGS. 2-10.

The receiver 120 may store or otherwise have access to MCS tables 121,timing parameters 122, and tone scaling parameters 123, which may be thesame as the MCS tables 111, the timing parameter 112, and the tonescaling parameters 113, respectively. The receiver 120 may include apacket extractor/decoder 124 that is configured to process receivedpackets, such as the received packet 130. For example, theextractor/decoder 124 may extract the MCS index from the packet 130. Theextractor/decoder 124 may identify a particular MCS table of the MCStables 121 that corresponds to the bandwidth and number of spatialstreams in use at the wireless network 140, and may search forcharacteristic values in the particular MCS table corresponding to theextracted MCS index. Based on the search, the extractor/decoder 124 maydetermine one or more encoding characteristics of the packet 130 and maydecode the packet 130 based on the encoding characteristic(s).

The packet 130 may comply with one of multiple frame formats (e.g., asingle user (SU) or “short” format and a multi user (MU) or “long”format) and may comply with various timing parameters. In a particularembodiment, the frame format is selected by the transmitter 110 orspecified by the receiver 120. The frame format may identify fields tobe included in the packet 130 and the order of the fields in the packet130. The timing parameters may indicate quantities and field durationsassociated with the packet 130. Thus, the frame format and/or timingparameters may be used in encoding and/or decoding of the packet 130. Adata structure (e.g., table) indicating timing parameters for differentframe formats may be stored at or otherwise accessible to transmittersand receivers. For example, the timing parameters may be stored in atable or array in a memory at the transmitter 110 as the timingparameters 112 and at the receiver 120 as the timing parameters 122.

In a particular embodiment, the frame format used for the packet 130 isbased at least in part on whether the underlying sub-1 GHz wirelessnetwork 140 is operating at 1 MHz bandwidth. For example, only the SUframe format may be available when the bandwidth is 1 MHz, but both theSU frame format and the MU frame format may be available for bandwidthsgreater than 1 MHz. In a particular embodiment, certain field durationsmay be longer when the bandwidth is 1 MHz than when the bandwidth isgreater than 1 MHz. Examples of frame formats and timing parameters arefurther described with reference to FIGS. 13-14.

The packet 130 may also be subjected to tone scaling. For example,different fields of the packet 130 may be tone scaled by a differentamount. Tone scaling parameters may be used in encoding and/or decodingof the packet. A data structure (e.g., table) indicating tone scalingparameters for different fields may be stored at or otherwise accessibleto transmitters and receivers. For example, the tone scaling parametersmay be stored in a table or array in a memory at the transmitter 110 asthe tone scaling parameters 113 and at the receiver 120 as tone scalingparameters 123. In a particular embodiment, different tone scalingparameters may be used based on whether the packet 130 is represented inthe SU frame format or in the MU frame format. Examples of tone scalingparameters are further described with reference to FIG. 16.

During operation, the transmitter 110 may create and encode the packet130 based on a selected MCS index and encoding characteristicsassociated therewith, a selected frame format, selected timingparameters, and/or selected tone scaling parameters. The bandwidth andnumber of spatial streams in use at the underlying sub-1 GHz wirelessnetwork 140 may also impact the creation and encoding of the packet 130.For example, the bandwidth and number of spatial streams may affect whatMCS indexes are available, what frame formats are available, and thevalues, or permitted range of values, of certain timing and tone scalingparameters. Upon receiving the packet 130, the receiver 120 may use theMCS index, the frame format, the timing parameters, and/or the selectedtone scaling parameters in processing (e.g., decoding) the packet 130.

The system 100 of FIG. 1 may thus provide standardized values of MCSindexes, frame formats, timing parameters, tone scaling parameters, andother message characteristics for use in a sub-1 GHz wireless network(e.g., an IEEE 802.11ah wireless network), where such values vary basedon characteristics (e.g., bandwidth and number of spatial streams) ofthe wireless network. Standardizing such PHY (e.g., Layer-1) and mediaaccess control (MAC) (e.g., Layer-2) messaging characteristics mayenable reliable communication via the sub-1 GHz wireless network.

FIGS. 2A-2C illustrate examples of the MCS tables 111 and the MCS tables121 of FIG. 1. In particular, FIGS. 2A-2C illustrate MCS tables for asub-1 GHz wireless network operating at 1 MHz bandwidth while using 1spatial stream.

MCS tables may include message characteristics for each of a pluralityof MCS indexes. For example, the MCS tables may indicate a modulationscheme (“Mod”), a coding rate (“R”), a number of bits per subcarriersymbol (“N_bpscs”), a number of data symbols (“N_sd”), and/or a numberof pilot symbols (“N_sp”) for each MCS index (“MCS Idx”). The MCS tablesmay also indicate a number of coded bits per OFDM symbol (“N_cbps”), anumber of data bits per OFDM symbol (“N_dbps”), a number of encodersused (“N_es”), data rate(s), and/or a guard interval (“GI”). Data ratesmay vary depending on whether an eight microsecond guard interval or afour microsecond guard interval is used.

In some embodiments, characteristics that are derivable from othercharacteristics may be omitted from the MCS tables. To illustrate, thenumber of coded bits per OFDM symbol may be derivable in accordance withthe formula N_cbps=N_sd*N_bpscs. The number of data bits per OFDM symbolmay be derivable in accordance with the formula N_dbps=N_cbps*R. In aparticular embodiment, the number of encoders may be determined based onthe formula N_es=ceiling(Data Rate/60 Mbps), where ceiling( ) is theinteger ceiling function. In some situations, the formula for N_es maybe modified, as further described herein.

In a particular embodiment, an MCS index for a given bandwidth andnumber of spatial streams may be unavailable if N_cbps/N_es is anon-integer, N_dbps/N_es is a non-integer, or if N_dbps is anon-integer. Such MCS indexes may be made unavailable for implementationsimplicity (e.g., so that puncture patterns are consistent between OFDMsymbols and so that extra padding symbols are not needed afterpuncturing/rate-matching). In a particular embodiment, to enable use ofsome MCS indexes that would otherwise be unavailable, the number ofencoders N_es may be modified so that N_cbps/N_es and/or N_dbps/N_esbecome integers, as further described herein.

As described above, each packet communicated via a sub-1 GHz network mayinclude an MCS index. The MCS index may be used to determine variouscharacteristics of the packet. Generally, when an MCS is selected, theMCS may be applied to the outgoing packet once. However, in a particularembodiment when 1 MHz bandwidth and 1 spatial stream are used, one ofthe available MCS indexes may correspond to a scenario in which an MCScorresponding to Mod=BPSK (binary phase-shift keying) and R=¼ is appliedtwice. As shown in FIG. 2, there may be at least three different optionsfor the MCS table corresponding to 1 MHz and 1 spatial stream. Accordingto a first option (designated “Option 1” in FIG. 2A), the repeat MCSscenario may have an MCS index of 0. According to a second option(designated “Option 2” in FIG. 2B), the repeat MCS scenario may have anMCS index of 10. According to a third option (designated “Option 3” inFIG. 2C), the repeat MCS scenario may have an MCS index of 15 (i.e., −1when a 4-bit MCS index is interpreted as two's complement).

FIGS. 3A-3C illustrate additional examples of the MCS tables 111 and theMCS tables 121 of FIG. 1. In particular, FIGS. 3A-3C illustrate MCStables for a sub-1 GHz wireless network operating at 1 MHz bandwidthwhile using 2, 3, or 4 spatial streams.

FIGS. 4A-4D illustrate additional examples of the MCS tables 111 and theMCS tables 121 of FIG. 1. In particular, FIGS. 4A-4D illustrate MCStables for a sub-1 GHz wireless network operating at 2 MHz bandwidthwhile using 1, 2, 3, or 4 spatial streams. As shown in FIGS. 4A, 4B, and4D via shading, MCS index 9 may be unavailable when operating at 2 MHzusing 1, 2, or 4 spatial streams, because N_dbps may be a non-integer.MCS indexes that are unavailable may be indicated as unavailable bybeing flagged (e.g., using an availability bit) or removed from an MCStable.

FIGS. 5A-5D illustrate additional examples of the MCS tables 111 and theMCS tables 121 of FIG. 1. In particular, FIGS. 5A-5D illustrate MCStables for a sub-1 GHz wireless network operating at 4 MHz bandwidthwhile using 1, 2, 3, or 4 spatial streams.

FIGS. 6A-6D illustrate additional examples of the MCS tables 111 and theMCS tables 121 of FIG. 1. In particular, FIGS. 6A-6D illustrate MCStables for a sub-1 GHz wireless network operating at 8 MHz bandwidthwhile using 1, 2, 3, or 4 spatial streams. As shown in FIG. 6C viashading, MCS index 6 may be unavailable when operating at 8 MHz using 3spatial streams, because N_dbps/N_es may be a non-integer.

FIGS. 7A-7D illustrate additional examples of the MCS tables 111 and theMCS tables 121 of FIG. 1. In particular, FIGS. 7A-7D illustrate MCStables for a sub-1 GHz wireless network operating at 16 MHz bandwidthwhile using 1, 2, or 3 spatial streams.

Two options are shown for the MCS table corresponding to 16 MHz and 3spatial streams. In the first option of FIG. 7C, MCS index 9 isunavailable, because N_dbps/N_es is a non-integer. However, as shown inthe second option of FIG. 7D, N_es may be increased from 5 to 6 for MCSindex 9, which changes N_dbps/N_es to an integer quantity and makes MCSindex 9 available. Thus, the number of encoders may be modified to makecertain MCS indexes available. In devices that would otherwise not usesix encoders, this modification may result in the addition of anencoder. However, in devices that use six encoders for otherbandwidth/spatial stream combinations (e.g., devices that support 4spatial streams at 16 MHz, as shown in FIG. 8), this modification may beperformed without adding additional hardware.

FIGS. 8A-8B illustrate additional examples of the MCS tables 111 and theMCS tables 121 of FIG. 1. In particular, FIGS. 8A-8B illustrate MCStables for a sub-1 GHz wireless network operating at 16 MHz bandwidthwhile using 4 spatial streams.

Two options are shown for the MCS table corresponding to 16 MHz, 4spatial streams. In the first option of FIG. 8A, MCS index 7 isunavailable, because N_cbps/N_es is a non-integer. However, as shown inthe second option of FIG. 8B, N_es may be increased from 5 to 6 for MCSindex 7, which changes N_cbps/N_es to an integer quantity and makes MCSindex 7 available.

In some embodiments, a single encoder may be used for allbandwidth/spatial stream combinations. As a result, N_dbps/N_es=N_dbpsand N_cbps/N_es=N_cbps, and additional MCS indexes may become available.When a single encoder is used, the MCS tables for 1 MHz with 1-4 spatialstreams, 2 MHz with 1-4 spatial streams, 4 MHz with 1-3 spatial streams,and 8 MHz with 1 spatial stream may be the same as described above, aseach row in those tables has N_es=1. Conversely, MCS tables that includeat least one row with N_es>1 may be modified, as shown in FIGS. 9-10.

FIGS. 9A-9D illustrate examples of the MCS tables 111 and the MCS tables121 of FIG. 1 when a single encoder is used for all bandwidth/spatialstream combinations. In particular, FIGS. 9A-9D illustrate MCS tablesfor a sub-1 GHz wireless network operating at 4 MHz bandwidth whileusing 4 spatial streams and at 8 MHz bandwidth while using 2, 3, or 4spatial streams, with a single encoder. Notably, MCS index 6 for 8 MHzand 3 spatial streams, which was shown as unavailable in FIG. 6C, isavailable in FIG. 9C because N_es=1.

FIGS. 10A-10D illustrate additional examples of the MCS tables 111 andthe MCS tables 121 of FIG. 1 when a single encoder is used for allbandwidth/spatial stream combinations. In particular, FIGS. 10A-10Dillustrate MCS tables for a sub-1 GHz wireless network operating at 16MHz bandwidth while using 1, 2, 3, or 4 spatial streams with a singleencoder. Notably, MCS index 9 for 16 MHz and 3 spatial streams, whichwas shown as unavailable in FIG. 7C unless N_es was increased from 5 to6, is available in FIG. 10C because N_es=1.

FIG. 11 is a flowchart of a particular embodiment of a method 1100 ofdetermining message characteristics based on an MCS index in a sub-1 GHzwireless network. In an illustrative embodiment, the method 1100 may beperformed by the receiver 120 of FIG. 1.

The method 1100 may include receiving, at a receiver from a transmitter,a packet via a sub-1 GHz wireless network operating at a particularbandwidth while using a particular number of spatial streams, at 1102.The wireless network may be an IEEE 802.11ah network. For example, inFIG. 1, the receiver 120 may receive the packet 130 from the transmitter110 via the wireless network 140.

The method 1100 may also include extracting an MCS index from thereceived packet, at 1104, and identifying a data structure stored at thereceiver, at 1106. The data structure may correspond to the particularbandwidth and the particular number of spatial streams. In a particularembodiment, the MCS index may be extracted from a SIG field of a PHYpreamble of the packet. For example, in FIG. 1, the extractor/decoder124 may extract an MCS index from the packet 130 and may identify one ofthe MCS tables 121 that corresponds to the bandwidth and number ofspatial streams. To illustrate, when the bandwidth is 4 MHz and 1spatial stream is in use, the identified MCS table may be the table atthe top of FIG. 5.

The method 1100 may further include determining, based on searching theidentified data structure for characteristic values corresponding to theextracted MCS index, at least one encoding characteristic of thereceived packet, at 1108. The encoding characteristic may include amodulation scheme, a coding rate, a number of bits per subcarriersymbol, a number of data symbols, a number of pilot symbols, a number ofcoded bits per OFDM symbol, a number of data bits per OFDM symbol, anumber of encoders, data rate(s), and/or a guard interval. Toillustrate, when the extracted MCS index is 5, it may be determined fromthe table at the top of FIG. 5, that Mod=64-QAM, R=⅔, N_bpscs=6,N_sd=108, N_sp=6, N_cbps=648, N_dbps=432, N_es=1, and/or datarate=10,800 Kbps with 8 microsecond GIs and/or 12,000 Kbps with 4microsecond GIs.

The method 1100 may include decoding the packet based on the at leastone encoding characteristic. For example, in FIG. 1, theextractor/decoder 124 may decode the packet 130 based on the at leastone encoding characteristic. To illustrate, the type of demodulation(e.g., binary phase-shift keying (BPSK), quadrature PSK (QPSK),quadrature amplitude modulation (QAM), etc.) applied to the packet 130may be determined based on the “Mod” characteristic in the MCS table atthe top of FIG. 5.

FIG. 12 is a flowchart of a particular embodiment of a method 1200 ofcontrolling message characteristics of messages communicated via a sub-1GHz wireless network based on an MCS index. In an illustrativeembodiment, the method 1200 may be performed by the transmitter 110 ofFIG. 1.

The method 1200 may include selecting, at a transmitter, an MCS from aplurality of MCSs available for use in communicating a packet via asub-1 GHz wireless network operating at a particular bandwidth whileusing a particular number of spatial streams, at 1202. For example, inFIG. 1, the transmitter 110 may select an available MCS from one of theMCS tables 111 that corresponds to the bandwidth and number of spatialstreams in use.

The method 1200 may also include determining at least one encodingcharacteristic based on an MCS index corresponding to the selected MCS,at 1204. The method 1200 may further include inserting the MCS indexinto the packet, at 1206, and encoding the packet based on the at leastone encoding characteristic, at 1208. For example, in FIG. 1, thecreator/encoder 114 may insert the MCS index into the packet 130 andencode the packet 130. The method 1200 may include sending the encodedpacket to a receiver, at 1210. For example, in FIG. 1, the transmitter110 may send the packet 130 to the receiver 120.

FIG. 13 is a diagram to illustrate particular embodiments of frameformats that may be used to represent the packet 130 of FIG. 1 and isgenerally designated 1300. In a particular embodiment, packetstransmitted via a sub-1 GHz network may comply with one of multipleframe formats, such as a single user (SU) frame format 1310 or a multiuser (MU) frame format 1320. Each frame format 1310, 1320 may specifyfields that are to be included in a packet and the order of such fields.

The SU frame format 1310 may include a short training field (STF) 1311,a long training field (LTF) 1312 (LTF_1), and a SIG field 1313. Whenmultiple spatial streams are in use, the SU frame format 1310 may alsoinclude additional LTFs 1314 (e.g., one additional LTF for eachadditional spatial stream). The STF 1311, the LTF 1312, the SIG field1313, and the additional LTFs 1314 may represent a packet preamble. TheSU frame format 1310 may also include a data portion 1315.

The MU frame format 1320 may include two portions: a first portionwithout precoding (designated as an omni portion 1330) and a secondportion with precoding (designated as an MU portion 1340). The omniportion 1330 may include a STF 1321, a first LTF 1322 (LTF_1), and asignal A (SIG-A) field 1323. The MU 1340 portion may include anadditional STF 1324 and, when more than one spatial stream is in use,one or more additional LTFs 1325. The MU portion 1340 may also include asignal B (SIG-B) field 1326 and a data portion 1327. In a particularembodiment, the SIG-B field 1326 may be present on a per-user basis. TheSTF and LTF_1 fields may be present in both the non-precoded omniportion 1330 and the precoded MU portion 1340 to assist a receiverfollowing an apparent channel conditions change between receipt andprocessing of the portions 1330 and 1340.

In a particular embodiment, the frame format selected by a transmittermay depend on the wireless network bandwidth in use. For example, onlythe SU frame format 1310 may be available when the bandwidth is 1 MHz,but both the SU frame format 1310 and the MU frame format 1320 may beavailable when the bandwidth is greater than 1 MHz (e.g., 2 MHz, 4 MHz,8 MHz, or 16 MHz).

In a particular embodiment, timing parameters associated with the SUframe format 1310 and the MU frame format 1320 may be stored at orotherwise accessible to a transmitter and/or a receiver. FIG. 14illustrates particular examples of timing parameters 1400 for the SUframe format 1310 and the MU frame format 1320. In an illustrativeembodiment, the timing parameters 1400 may be the timing parameters 112and/or the timing parameters 122 of FIG. 1.

In a particular embodiment, one or more of the timing parameters 1400 ofa packet (e.g., the packet 130 of FIG. 1) may vary depending on thebandwidth (e.g., 1 MHz, 2 MHz, 4 MHz, 8 MHz, or 16 MHz) and/or number ofspatial streams (1, 2, 3, or 4) in use. The timing parameters 1400 mayinclude a number of complex data subcarriers N_sd, a number of pilotsubcarriers N_sp, a number of total subcarriers (excluding guards) N_st,a highest subcarrier index N_sr, a subcarrier frequency spacing delta_f,an inverse discrete Fourier transform (IDFT) and DFT period T_dft, aguard interval duration T_gi, a double guard interval duration T_gi2, ashort guard interval duration T_gis, an OFDM symbol duration with longintervals T_syml, an OFDM symbol duration with short guard intervalsT_syms, a number of SERVICE field bits N_service, and/or a number oftail bits per binary convolution code (BCC) encoder Ntail.

The timing parameters 1400 may include a STF duration for SU and MUframe formats T_stf, a LTF_1 duration for SU and MU formats T_ltf1, aSIG field and SIG-A field duration T_sig, a second LTF duration foradditional LTFs T_mimo_ltf, a second STF duration for MU frame formatT_mu_stf, and/or a SIG-B field duration T_sig_b. Some timing parameters1400 may have different values depending on the bandwidth in use. Forexample, the STF duration T_stf, the LTF1 duration T_ltf1, and theSIG/SIG-A field duration T_sig may each be longer when the bandwidth is1 MHz than when the bandwidth is greater than 1 MHz. In a particularembodiment, one or more of the timing parameters may be interrelated, asshown in FIG. 14. Thus, timing parameters that are derivable from othertiming parameters may be omitted from a table storing the timingparameters 1400.

FIG. 15 is a flowchart of a particular embodiment of a method 1500 ofcontrolling a frame format and timing parameters in a sub-1 GHz wirelessnetwork. In an illustrative embodiment, the method 1500 may be performedby the transmitter 110 of FIG. 1.

The method 1500 may include determining, at a transmitter, that a packetis to be sent to a receiver, at 1502, and determining a wireless networkbandwidth, at 1504. For example, in FIG. 1, the transmitter 110 maydetermine that the packet 130 is to be sent to the receiver 120 and maydetermine (e.g., based on information from an access point orexamination of messaging data) the bandwidth of the sub-1 GHz wirelessnetwork 140.

When the bandwidth is 1 MHz, the method 1500 may include selecting a SUframe format for use in communicating the packet, at 1506. For example,the SU frame format may be the SU frame format 1310 of FIG. 13. When thebandwidth is greater than 1 MHz, the method 1500 may include selectingthe SU frame format or a MU frame format, at 1508. For example, the MUframe format may be the MU frame format 1320 of FIG. 13.

The method 1500 may also include generating the packet in accordancewith the selected frame format and based on one or more timingparameters associated with the selected frame format, at 1510. Forexample, the timing parameters may be one or more of the timingparameters 1400 of FIG. 14. The method 1500 may further include sendingthe packet from the transmitter to the receiver, at 1512. For example,in FIG. 1, the transmitter 110 may send the packet 130 to the receiver120.

FIG. 16 illustrates particular examples of tone scaling parameters 1600.In an illustrative embodiment, the tone scaling parameters 1600 may bethe tone scaling parameters 113 and/or the tone scaling parameters 123of FIG. 1.

When a packet (e.g., the packet 130 of FIG. 1) is generated, one or morefields of the packet may be scaled by one or more tone scalingparameters. Different tone scaling parameters may be applied todifferent fields of the same packet. In particular embodiment, tonescaling parameters may be a function of frame format (e.g., whether thepacket is in the SU frame format 1310 of FIG. 13 or the MU frame format1320 of FIG. 13), bandwidth, and/or number of spatial streams in use.

For example, the tone scaling parameters 1600 may include parameters forthe SU frame format at 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHzbandwidths, including a STF tone scaling parameter, a LTF_1 tone scalingparameter, a SIG field tone scaling parameter, and a data portion tonescaling parameter. A multiple-input multiple-output LTF (MIMO-LTF) tonescaling parameter may also be applied when more than one spatial streamis in use. At 1 MHz bandwidth, the SIG field and the data portion mayhave the same number of available tones, and therefore the same tonescaling parameter. At higher bandwidths, the SIG field may be generatedby repeating a lower bandwidth SIG field. Thus, the SIG field tonescaling parameter may double (e.g., from 26 to 52, 104, 208, and 416) asthe bandwidth doubles (e.g., from 1 MHz to 2 MHz, 4 MHz, 8 MHz, and 16MHz), as shown in FIG. 16. However, the data portion tone scalingparameter may not double. Thus, the SIG field tone scaling parameter andthe data portion tone scaling parameter may be different for somebandwidths.

As explained above with reference to FIG. 13, the MU frame format maynot be available at 1 MHz bandwidth. In FIG. 16, the tone scalingparameters 1600 for the MU frame format at 1 MHz are shaded to indicatethis unavailability. For the MU frame format at bandwidths greater than1 MHz, the tone scaling parameters 1600 may include a STF tone scalingparameter, a LTF_1 tone scaling parameter, a SIG-A field tone scalingparameter, a SIG-B field tone scaling parameter, a data portion tonescaling parameter, and a MU-STF tone scaling parameter. A MIMO-LTF tonescaling parameter may also be applied when more than one spatial streamis in use. The SIG-A field tone scaling parameter may double as thebandwidth doubles, but the SIG-B field tone scaling parameter and thedata portion tone scaling parameter may not double. Thus, the SIG-Afield tone scaling parameter may be different than the data portion tonescaling parameter for some bandwidths. The SIG-B tone scaling parametermay be the same as the data portion tone scaling parameter for eachbandwidth, as shown in FIG. 16.

FIG. 17 is a flowchart of a particular embodiment of a method 1700 ofcontrolling tone scaling parameters in a sub-1 GHz wireless network. Inan illustrative embodiment, the method 1700 may be performed by thetransmitter 110 of FIG. 1.

The method 1700 may include selecting, at a transmitter, one or moretone scaling parameters for use in communicating a packet via a sub-1GHz wireless network operating at a particular bandwidth, at 1702. Theone or more tone scaling parameters may be selected based at least inpart on a frame format of the packet and the particular bandwidth. Forexample, in FIG. 1, the transmitter 110 may select one or more of thetone scaling parameters 113. In an illustrative embodiment, the tonescaling parameters may be one or more of the tone scaling parameters1600 of FIG. 16.

The method 1700 may also include generating the packet, includingscaling one or more fields of the packet in accordance with the one ormore tone scaling parameters, at 1704. For example, fields such as STF,LTF_1, SIG, MIMO-LTF, and/or data may be scaled by tone scalingparameters when the packet is a SU frame format packet and thebandwidths is greater than or equal to 1 MHz. As another example, fieldssuch as STF, LTF_1, SIG-A, MU-STF, MIMO-LTF, SIG-B, and/or data may bescaled when the packet is a MU frame format packet and the bandwidth isgreater than 1 MHz.

The method 1700 may further include sending the packet from thetransmitter to the receiver, at 1706. For example, in FIG. 1, thetransmitter 110 may send the packet 130 to the receiver 120.

It should be noted although various data structures have been shown anddescribed as tables, other types of data structures may be used inconjunction with the described techniques. Moreover, some datastructures may be combined while others may be split. For example,instead of using a different MCS table for each bandwidth/spatial streamcombination, a particular embodiment may utilize a single MCS table thatis indexed by bandwidth, number of spatial streams, and MCS index. Asanother example, instead of using a single timing parameter table ortone scaling parameter table, multiple tables may be used (e.g.,different tables for each bandwidth, frame format, or bandwidth/frameformat combination). Thus, more, fewer, and/or different types of datastructures than those illustrated may be used in conjunction with thedescribed techniques.

FIG. 18 is a block diagram of a mobile communication device 1800. In aparticular embodiment, the mobile communication device 1800, orcomponents thereof, include or are included within the transmitter 110FIG. 1, the receiver 120 of FIG. 1, a transceiver, or any combinationthereof. Further, all or part of the methods described in FIGS. 11, 12,15, and/or 17 may be performed at or by the mobile communication device1800, or components thereof. The mobile communication device 1800includes a processor 1810, such as a digital signal processor (DSP),coupled to a memory 1832.

The memory 1832 may be a non-transitory tangible computer-readableand/or processor-readable storage device that stores instructions 1860.The instructions 1860 may be executable by the processor 1810 to performone or more functions or methods described herein, such as the methodsdescribed with reference to FIGS. 11, 12, 15, and/or 17. The memory 1832may also store MCS tables 1861, timing parameters 1862, and tone scalingparameters 1863. The MCS tables 1861 may include the MCS tables 111 ofFIG. 1, the MCS tables 121 of FIG. 1, the MCS tables illustrated inFIGS. 2-10, or any combination thereof. The timing parameters 1862 mayinclude the timing parameters 112 of FIG. 1, the timing parameters 122of FIG. 1, the timing parameters 1400 of FIG. 14, or any combinationthereof. The tone scaling parameters 1863 may include the tone scalingparameters 113 of FIG. 1, the tone scaling parameters 123 of FIG. 1, thetone scaling parameters 1600 of FIG. 16, or any combination thereof.

The processor 1810 may also include, implement, or execute instructionsrelated to device components described herein. For example, theprocessor 1810 may include or implement an encoder 1891 (e.g., thepacket creator/encoder 114 of FIG. 1) and/or a decoder 1892 (e.g., thepacket extractor/decoder 124 of FIG. 1).

FIG. 18 also shows a display controller 1826 that is coupled to theprocessor 1810 and to a display 1828. A coder/decoder (CODEC) 1834 canalso be coupled to the processor 1810. A speaker 1836 and a microphone1838 can be coupled to the CODEC 1834. FIG. 18 also indicates that awireless controller 1840 can be coupled to the processor 1810, where thewireless controller 1840 is in communication with an antenna 1842 via atransceiver 1850. The wireless controller 1840, the transceiver 1850,and the antenna 1842 may thus represent a wireless interface thatenables wireless communication by the mobile communication device 1800.For example, the wireless communication may be via a sub-1 GHz wirelessnetwork (e.g., an IEEE 802.11ah wireless network), such as the wirelessnetwork 140 of FIG. 1. Such a wireless interface may be used to send orreceive the packet 130 of FIG. 1. The mobile communication device 1800may include numerous wireless interfaces, where different wirelessnetworks are configured to support different networking technologies orcombinations of networking technologies.

It should be noted that although FIG. 18 illustrates a mobilecommunication device, other types of devices may communicate via a sub-1GHz wireless network (e.g., an IEEE 802.11ah wireless network). Somedevices may include more, fewer, and/or different components than thoseillustrated in FIG. 18. For example, an IEEE 802.11ah wireless sensormay not include the display 1828, the speaker 1836, or the microphone1838.

In a particular embodiment, the processor 1810, the display controller1826, the memory 1832, the CODEC 1834, the wireless controller 1840, andthe transceiver 1850 are included in a system-in-package orsystem-on-chip device 1822. In a particular embodiment, an input device1830 and a power supply 1844 are coupled to the system-on-chip device1822. Moreover, in a particular embodiment, as illustrated in FIG. 18,the display device 1828, the input device 1830, the speaker 1836, themicrophone 1838, the antenna 1842, and the power supply 1844 areexternal to the system-on-chip device 1822. However, each of the displaydevice 1828, the input device 1830, the speaker 1836, the microphone1838, the antenna 1842, and the power supply 1844 can be coupled to acomponent of the system-on-chip device 1822, such as an interface or acontroller.

In conjunction with the described embodiments, an apparatus includesmeans for storing one or more data structures. The one or more datastructures indicate timing parameters for a plurality of frame formatsand a plurality of bandwidths of a sub-one gigahertz wireless network.For example, the means for storing may include a component (e.g., amemory or data storage device) of the transmitter 110 of FIG. 1, acomponent (e.g., a memory or data storage device) of the receiver 120 ofFIG. 1, the memory 1832 of FIG. 18, another device configured to storedata, or any combination thereof. The apparatus also includes means forselecting a frame format for use in communicating a packet via thesub-one gigahertz wireless network operating at a particular bandwidth.The frame format is selected based at least in part on the particularbandwidth. For example, the means for selecting may include the packetcreator/encoder 114 of FIG. 1, the packet extractor/decoder 124 of FIG.1, the processor 1810 of FIG. 18, the encoder 1891 of FIG. 18, thedecoder 1892 of FIG. 18, another device configured to select a frameformat, or any combination thereof.

The apparatus further includes means for determining one or more timingparameters based on the selected frame format and the particularbandwidth. For example, the means for determining may include the packetcreator/encoder 114 of FIG. 1, the packet extractor/decoder 124 of FIG.1, the processor 1810 of FIG. 18, the encoder 1891 of FIG. 18, thedecoder 1892 of FIG. 18, another device configured to determine timingparameter(s), or any combination thereof. The apparatus includes meansfor generating the packet in accordance with the selected frame formatand the one or more timing parameters. For example, the means forgenerating may include the packet creator/encoder 114 of FIG. 1, thepacket extractor/decoder 124 of FIG. 1, the processor 1810 of FIG. 18,the encoder 1891 of FIG. 18, the decoder 1892 of FIG. 18, another deviceconfigured to generate a packet, or any combination thereof.

Those of skill would further appreciate that the various illustrativelogical blocks, configurations, modules, circuits, and algorithm stepsdescribed in connection with the embodiments disclosed herein may beimplemented as electronic hardware, computer software, or combinationsof both. Various illustrative components, blocks, configurations,modules, circuits, and steps have been described above generally interms of their functionality. Whether such functionality is implementedas hardware or software depends upon the particular application anddesign constraints imposed on the overall system. Skilled artisans mayimplement the described functionality in varying ways for eachparticular application, but such implementation decisions should not beinterpreted as causing a departure from the scope of the presentdisclosure.

The steps of a method or algorithm described in connection with theembodiments disclosed herein may be embodied directly in hardware, in asoftware module executed by a processor, or in a combination of the two.A software module may reside in random access memory (RAM), flashmemory, read-only memory (ROM), programmable read-only memory (PROM),erasable programmable read-only memory (EPROM), electrically erasableprogrammable read-only memory (EEPROM), registers, hard disk, aremovable disk, a compact disc read-only memory (CD-ROM), or any otherform of non-transitory storage medium known in the art. An exemplarystorage medium is coupled to the processor such that the processor canread information from, and write information to, the storage medium. Inthe alternative, the storage medium may be integral to the processor.The processor and the storage medium may reside in anapplication-specific integrated circuit (ASIC). The ASIC may reside in acomputing device or a user terminal (e.g., a mobile phone or a PDA). Inthe alternative, the processor and the storage medium may reside asdiscrete components in a computing device or user terminal.

The previous description of the disclosed embodiments is provided toenable a person skilled in the art to make or use the disclosedembodiments. Various modifications to these embodiments will be readilyapparent to those skilled in the art, and the principles defined hereinmay be applied to other embodiments without departing from the scope ofthe disclosure. Thus, the present disclosure is not intended to belimited to the embodiments disclosed herein but is to be accorded thewidest scope possible consistent with the principles and novel featuresas defined by the following claims.

What is claimed is:
 1. A method comprising: selecting, at a transmitter,a frame format for use in transmission of a packet via a wirelessnetwork, the transmission associated with a particular bandwidth,wherein the selected frame format is a first frame format if theparticular bandwidth is equal to a threshold bandwidth, wherein theselected frame format is the first frame format or a second frame formatif the particular bandwidth is greater than the threshold bandwidth,wherein the second frame format comprises a first portion and a secondportion, wherein the first portion comprises a short training field(STF), a long training field (LTF), and a signal A field (SIG-A), andwherein the second portion comprises a data portion including a secondSTF, one or more signal B fields (SIG-Bs), and a data field; determiningone or more timing parameters based on the selected frame format and theparticular bandwidth; generating the packet in accordance with theselected frame format and the one or more timing parameters; and sendingthe packet from the transmitter to a receiver.
 2. The method of claim 1,wherein the wireless network operates in accordance with an Institute ofElectrical and Electronics Engineers (IEEE) 802.11ah protocol.
 3. Themethod of claim 1, wherein the first frame format comprises a third STF,a second LTF, a signal field (SIG), and a second data field.
 4. Themethod of claim 3, wherein if more than one spatial stream is associatedwith the transmission, the first frame format further comprises one ormore additional LTFs.
 5. The method of claim 1, wherein if more than onespatial stream is associated with the transmission, the second frameformat further comprises one or more additional LTFs.
 6. The method ofclaim 1, wherein the particular bandwidth is equal to 1 megahertz (MHz),2 MHz, 4 MHz, 8 MHz, or 16 MHz.
 7. The method of claim 1, wherein thethreshold bandwidth is equal to 1 MHz.
 8. The method of claim 1, whereinthe one or more timing parameters include: a number of complex datasubcarriers; a number of pilot subcarriers; a number of totalsubcarriers excluding guards; a highest data subcarrier index; asubcarrier frequency spacing; a discrete Fourier transform (DFT) period;an inverse DFT (IDFT) period; a guard interval duration; a double guardinterval duration; a short guard interval duration; an orthogonalfrequency-division multiplexing (OFDM) symbol duration with long guardintervals; an OFDM symbol duration with short guard intervals; an OFDMsymbol duration; a number of bits in a SERVICE field; a number of tailbits per binary convolution code encoder; a short training field (STF)duration; a long training field (LTF) duration; a signal field (SIG)duration; a signal A field (SIG-A) duration; a multiple-inputmultiple-output LTF (MIMO-LTF) duration; a long format STF duration; asignal B field (SIG-B) duration; or any combination thereof.
 9. Themethod of claim 8, wherein the STF duration, the LTF duration, and oneof the SIG duration and the SIG-A duration are each longer if theparticular bandwidth is equal to the threshold bandwidth than if theparticular bandwidth is greater than the threshold bandwidth.
 10. Themethod of claim 8, wherein: the subcarrier frequency spacing is 31.25kilohertz (KHz); the DFT period is 32 microseconds (μs); the IDFT periodis 32 μs; the guard interval duration is 8 μs; the double guard intervalduration is 16 μs; the short guard interval duration is 4 μs; the OFDMsymbol duration with long guard intervals is 40 μs; the OFDM symbolduration with short guard intervals is 36 μs; the OFDM symbol durationis 40 μs or 36 μs; the number of bits in the SERVICE field is 16; thenumber of tail bits per binary convolution code encoder is 6; and theMIMO-LTF duration is 40 μs.
 11. The method of claim 8, wherein if theparticular bandwidth is 1 megahertz (MHz): the number of complex datasubcarriers is 24; the number of pilot subcarriers is 2; the number oftotal subcarriers excluding guards is 26; the highest data subcarrierindex is 13; the STF duration is 160 microseconds (μs); the LTF durationis 160 μs; and the SIG duration is 240 μs or 200 μs.
 12. The method ofclaim 8, wherein if the particular bandwidth is greater than 1 megahertz(MHz): the STF duration is 80 microseconds (μs); the LTF duration is 8μs; the SIG duration is 80 μs; the SIG-A duration is 80 μs; the longformat STF duration is 40 μs; and the SIG-B duration is 40 μs.
 13. Themethod of claim 8, wherein if the particular bandwidth is 2 megahertz(MHz): the number of complex data subcarriers is 52; the number of pilotsubcarriers is 4; the number of total subcarriers excluding guards is56; and the highest data subcarrier index is
 28. 14. The method of claim8, wherein if the particular bandwidth is 4 megahertz (MHz): the numberof complex data subcarriers is 108; the number of pilot subcarriers is6; the number of total subcarriers excluding guards is 114; and thehighest data subcarrier index is
 58. 15. The method of claim 8, whereinif the particular bandwidth is 8 megahertz (MHz): the number of complexdata subcarriers is 234; the number of pilot subcarriers is 8; thenumber of total subcarriers excluding guards is 242; and the highestdata subcarrier index is
 122. 16. The method of claim 8, wherein if theparticular bandwidth is 16 megahertz (MHz): the number of complex datasubcarriers is 468; the number of pilot subcarriers is 16; the number oftotal subcarriers excluding guards is 484; and the highest datasubcarrier index is
 250. 17. A non-transitory processor-readable mediumstoring: one or more data structures, the one or more data structuresindicating timing parameters for a first frame format and a second frameformat of a wireless network, wherein a particular bandwidth isassociated with the first frame format if the particular bandwidth isequal to a threshold bandwidth, wherein the particular bandwidth isassociated with the first frame format or the second frame format if theparticular bandwidth is greater than the threshold bandwidth, whereinthe second frame format comprises a first portion and a second portion,wherein the first portion comprises a short training field (STF), a longtraining field (LTF), and a signal A field (SIG-A), and wherein thesecond portion comprises a data portion including a second STF, one ormore signal B fields (SIG-Bs), and a data field; wherein the timingparameters include: a number of complex data subcarriers; a number ofpilot subcarriers; a number of total subcarriers excluding guards; ahighest data subcarrier index; a subcarrier frequency spacing; aninverse discrete Fourier transform period; a discrete Fourier transformperiod; a guard interval duration; a double guard interval duration; ashort guard interval duration; an orthogonal frequency-divisionmultiplexing (OFDM) symbol duration with long guard intervals; an OFDMsymbol duration with short guard intervals; an OFDM symbol duration; anumber of bits in a SERVICE field; a number of tail bits per binaryconvolution code encoder; a short training field (STF) duration; a longtraining field (LTF) duration; a signal field (SIG) duration; a signal Afield (SIG-A) duration; a multiple-input multiple-output LTF (MIMO-LTF)duration; a long format STF duration; a signal B field (SIG-B) duration;or any combination thereof.
 18. The non-transitory processor-readablemedium of claim 17, wherein the one or more data structures furtherindicate tone scaling parameters associated with the first frame formatand the second frame format.
 19. The non-transitory processor-readablemedium of claim 17, wherein the first frame format comprises a thirdSTF, a second LTF, a signal field (SIG), and a second data field. 20.The non-transitory processor-readable medium of claim 19, wherein theSIG field is scaled by a tone scaling parameter that is based on theparticular bandwidth.
 21. An apparatus comprising: a memory storing oneor more data structures associated with a wireless network; and aprocessor coupled to the memory, the processor configured to: select aframe format for use in transmission of a packet via the wirelessnetwork, the transmission associated with a particular bandwidth,wherein the selected frame format is a first frame format if theparticular bandwidth is equal to a threshold bandwidth, wherein theselected frame format is the first frame format or a second frame formatif the particular bandwidth is greater than the threshold bandwidth,wherein the second frame format comprises a first portion and a secondportion, wherein the first portion comprises a short training field(STF), a long training field (LTF), and a signal A field (SIG-A), andwherein the second portion comprises a data portion including a secondSTF, one or more signal B fields (SIG-Bs), and a data field; determineone or more timing parameters based on the selected frame format and theparticular bandwidth; and generate the packet in accordance with theselected frame format and the one or more timing parameters.
 22. Theapparatus of claim 21, wherein the wireless network operates inaccordance with an Institute of Electrical and Electronics Engineers(IEEE) 802.11ah protocol.
 23. An apparatus comprising: means for storingone or more data structures associated with a wireless network; meansfor selecting a frame format for use in transmission of a packet via thewireless network, the transmission associated with a particularbandwidth, wherein the selected frame format is a first frame format ifthe particular bandwidth is equal to a threshold bandwidth, wherein theselected frame format is the first frame format or a second frame formatif the particular bandwidth is greater than the threshold bandwidth,wherein the second frame format comprises a first portion and a secondportion, wherein the first portion comprises a short training field(STF), a long training field (LTF), and a signal A field (SIG-A), andwherein the second portion comprises a data portion including a secondSTF, one or more signal B fields (SIG-Bs), and a data field; means fordetermining one or more timing parameters based on the selected frameformat and the particular bandwidth; and means for generating the packetin accordance with the selected frame format and the one or more timingparameters.
 24. The apparatus of claim 23, further comprising means forselecting tone scaling parameters based on selection of the first frameformat or the second frame format.
 25. The apparatus of claim 23,further comprising means for scaling one or more fields of the firstframe format or one or more fields of the second frame format based onthe particular bandwidth, wherein the one or more fields of the secondframe format include the STF, the LTF, the SIG-A, the second STF, theone or more SIG-Bs, and the data field.
 26. The apparatus of claim 25,wherein if the particular bandwidth is 2 megahertz (MHz): the STF isscaled by a factor of 12; the LTF is scaled by a factor of 56; the SIG-Ais scaled by a factor of 52; the second STF is scaled by a factor of 12;the one or more SIG-Bs are scaled by a factor of 56; and the data fieldis scaled by a factor of
 56. 27. The apparatus of claim 25, wherein ifthe particular bandwidth is 4 MHz: the STF is scaled by a factor of 24;the LTF is scaled by a factor of 114; the SIG-A is scaled by a factor of104; the second STF is scaled by a factor of 24; the one or more SIG-Bsare scaled by a factor of 114; and the data field is scaled by a factorof
 114. 28. The apparatus of claim 25, wherein if the particularbandwidth is 8 MHz: the STF is scaled by a factor of 48; the LTF isscaled by a factor of 242; the SIG-A is scaled by a factor of 208; thesecond STF is scaled by a factor of 48; the one or more SIG-Bs arescaled by a factor of 242; and the data field is scaled by a factor of242.
 29. The apparatus of claim 25, wherein if the particular bandwidthis 16 MHz: the STF is scaled by a factor of 96; the LTF is scaled by afactor of 484; the SIG-A is scaled by a factor of 416; the second STF isscaled by a factor of 96; the one or more SIG-Bs are scaled by a factorof 484; and the data field is scaled by a factor of
 484. 30. Theapparatus of claim 23, wherein the SIG-A is scaled by a tone scalingparameter that is based on the particular bandwidth.